Vehicle tracking system using smart-phone as active transponder

ABSTRACT

A system is described for tracking vehicle position using a smart phone or similar device as an active transponder that communicates with roadside equipment. The system may uses existing RF transceivers on the smart-phone, such as Bluetooth® LE or WiFi to periodically transmit an identifying message. Road-based equipment detects and locates the smart phone. In a further aspect, the smart phone is alerted by roadside beacons and responds with identification information. Transaction processing may be performed either on the smart phone or by roadside or back office equipment. The system may be used for automated roadway tolling and monitoring and also for access control. A coded card may be scanned by the smart card to enter identification for access control.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/136,884 filed on Sep. 20, 2018, which is a continuation of U.S.patent application Ser. No. 15/597,778 filed on May 17, 2017, now U.S.Pat. No. 10,134,210, both of which are hereby incorporated herein byreference.

BACKGROUND

The field of electronic vehicle tracking for tolling and other purposeshas seen many iterations over the years. These include the use ofvehicle-based backscatter transponders detected and communicated with byroadside equipment, active transponders detected and communicated withby roadside equipment, hybrid transponders having both active andbackscatter functions; and video monitoring of vehicle license plate andother placards. Cellular telephones have also been described for use intolling systems, alone or in combination with the aforementioned typesof transponders.

One problem in tolling applications that exists regardless of thetechnology used is determination of the roadway lane in which thevehicle is travelling. This is critical for several reasons. Firstly,because open road tolling systems frequently employ multiple transponderdetection antennas and systems to cover multiple lanes of travel, it isnecessary to accurately determine lane of travel so that vehicles arenot recorded more than once per crossing and so that ancillarylane-based detection equipment such as light curtains, treadles andlicense plate cameras are coordinated with the correct lane of travel ofthe detected vehicle. Secondly, various tolling and roadway trafficmanagement operations provide incentives and/or restrictions forvehicles of different types and occupancy levels, these include theability to travel in restricted lanes, thus it is necessary to determineif a vehicle is travelling in the required or allowed lane.

Another use of vehicle-based transponder technology is providing secureaccess to limited access facilities. While tolling agencies may registertolling transponders based on vehicle identification data such aslicense plates, such a system may be impractical for issuing devices toaccess a facility because, for instance, the user may legitimately usedifferent vehicles. In these cases issuing access devices to an end usermay be made on a different basis than vehicle identification. The use ofsmart phones as transponders in to provide access to gated facilitiesprovides opportunities to arrange access that is not limited to a singleuser vehicle and that uses a device the user already has and is notlikely leave in an unused vehicle.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram of an exemplary system using a smart phone as atransponder.

FIG. 2 is a diagram of a further exemplary system using a smart phone asa transponder.

FIG. 3 is a diagram of a further exemplary system using a smart phone asa transponder.

FIG. 4 is a diagram of an exemplary smart phone for use in a systemusing a smart phone as a transponder.

FIG. 5 is test results of a test-setup using two Butler Matrix antennaarrays.

FIG. 6 is a graph of RSSI versus time for beacons in two locations.

FIG. 7 is an exemplary gate access system using a smart phone as atransponder.

FIG. 8 is a front view of an access card for use with a system using asmart phone as a transponder.

FIG. 9 is an exemplary process for registering a smart phone for gateaccess using a unique identification card.

DETAILED DESCRIPTION

Those skilled in the art will recognize other detailed designs andmethods that can be developed employing the teachings of the presentinvention. The examples provided here are illustrative and do not limitthe scope of the invention, which is defined by the attached claims. Thefollowing detailed description refers to the accompanying drawings. Thesame reference numbers in different drawings may identify the same orsimilar elements.

Aspects of the present invention are directed to novel approaches tovehicle tracking and tolling using smart phones or otherwireless-enabled personal devices including smart watches and tabletcomputers and as active transponders. A smart phone is defined here as acellular phone that also has capability to load and run applicationprograms (apps) and that has wireless transceivers beyond the radio usedto send voice and data to a cellular network. Smart watches at presenthave all of these capabilities except for the ability to directly sendvoice and data over a cellular network, which are typically accessed viaa smart phone associated with the smart watch.

In an exemplary embodiment, the system consists of vehicle-based smartphones interacting with external fixed transceivers mounted over theroadway or beside it. The phones and external transceivers are capableof two-way communications, and both transmit and receive functions canbe utilized in the system.

The system may take several forms: The phone may transmit data to one ormore fixed transceivers. The phone may receive data from one or morefixed transceivers. There may be two-way communication between the fixedtransceiver(s) and phone. The wireless protocol used between the phoneand the transceiver(s) may be Bluetooth® low energy (BLE), IEEE802.11/WiFi, or an emergent protocol yet to be widespread. A fixedtransceiver may utilize a multi-beam antenna. A fixed transceiver mayutilize one or more antennas, each providing a single beam covering asingle lane or geographic area.

Determination of the vehicle's lane of travel or area may be computedby: a controller in communication with the fixed transceivers, or by thesmart phone or like devices including smart watches. In this case, thesmart phone can transmit its lane number or area to a back office via acellular network, WiFi, BLE, RFID, or any other wireless protocol in usein the phone.

In one aspect a smart phone, shown in FIG. 4, is configured withdedicated application software to perform as an active transponder forvehicle tracking and/or roadway tolling. The smart phone is adapted totransmit a message periodically that contains a known address oridentifier. An exemplary system is described with reference to FIGS.1-4, with like numbers representing the indicated elements. An existingradio supported on the smart phone 1 such as the WiFi radio 15 or theBLE radio 13 can be used to generate these signals. The smart phone mayalso include a GPS receiver/processor 14, application software 17 forthe phone-as-active-transponder function, and a wide area cellularnetwork transceiver 16. Roadside and/or overhead transceivers 8, 9detect the transmissions to identify the location of the vehicle 2. Thephone 1 must be uniquely associated with data content in the messagewhich is associated with an account used to collect the payment oftolls.

To ensure that valid uncorrupted messages from the phone are received bythe roadside equipment with the vehicle moving, it is necessary that thephone 1 send messages frequently while within the toll zone. A minimumrepetition rate of 10 Hz, or one per 100 milliseconds, is required, but100 Hz or one per 10 milliseconds is preferred. Depending upon powerconsumption in this high rep rate mode, it may be necessary to overlayGeoZone functionality, such that the higher rep rate/power consumptionmode operates only in the vicinity of toll collection zones, thuscreating a low duty cycle operation to preserve cell phone batterycapacity. GeoZone functionality can be implemented by comparing currentGPS position (established by phone's internal GPS receiver/processor 14to stored geo-location zones selected to include toll point locations. Acurrent limitation on this approach is that the maximum number ofGeoZones in an iPhone® is 20. Alternate methods include using BLEbeacons 9 to indicate to the phone application 17 that it is in thevicinity of a toll collection point, or by using WiFi AP's 8 SSID's orMAC addresses that are detected by the phone using the phone's WiFiradio 15.

Standard radio protocols such as WiFi and BLE may be used for thetransaction, and in principal any protocol with relevant hardware in thephone may be used subject to practical restrictions inherent in theprotocol, hardware, and phone software. WiFi probe requests and BLEadvertisements are examples of signal formats that can function asbeacons in this system. The system can rely on this message alone forlane determination, or additionally utilize responses to the beacon.

To communicate with the smart phone app, fixed transceivers that utilizeWiFi and/or BLE protocols are installed in the lane and connected toappropriate antennas. Messages from the phone contain a uniqueidentifier or ID; these messages can be evaluated for received signalstrength indication (RSSI). Lane position or proximate antenna positioncan be determined at a roadside server connected to the transceivers byEthernet and TCP/IP or other convenient protocol. When a phone messageis received at more than one transceiver across the roadway, the uniqueidentifier, along with the RSSI, are sent to the server. Alternately,the lane determination may be made by the phone application resident andrunning on the phone, based on messages sent from the fixed transceiversto the phone.

The basic concept of identifying the travel lane relies on RSSI,provided by common WiFi and BLE transceivers used in mobile phones andfixed transceivers. RSSI-based algorithms for range and directiondetermination must be used with care owing to effects including:multipath corruption, occurring when the radio wave from a transmitterbounces off obstacles in its path and arrives at the target withrelatively small time offsets from the direct path; antenna patternswith nulls in particular directions; and sensitivity to polarization.

In one approach, as shown in FIG. 1, a smart phone 1 in a vehicle 2transmits a message via WiFi or BLE. The roadside equipment includes agantry 5 on which are mounted one antenna 6 per lane of travel. Theantennas are connected to a receiver 21 which is connected via datalines 22 to a roadside server 20. The system may also include wide-beamreceiving antennas 4 and multi-beam Butler matrix antennas 3, asdescribed further below. The server looks only at messages that meet aminimum threshold signal strength received from the smart phone 1, thencompares the signal strengths received from each antenna 6 to determinethe strongest one over a specified period on the order of 30 ms. As thesmart phone 1 traverses the roadway, each period has a count assignedbased on the strongest signal strength received on an antenna. The mostproximate antenna or alternatively the lane of travel is determined tobe the antenna or lane with the most counts in a larger second period(roughly 300 ms) or the total such counts during a the entire periodrequired to traverse the section of roadway.

FIG. 3 shows an exemplary design using multi-beam antennas 3 fed byButler matrices, creating highly directional beam patterns 30, 30′, 31,31′, 32 and 32′. By determining the strongest signal path between eachantenna and the phone, either received from the smart phone, it ispossible to very accurately determine position of the phone andpresumable the vehicle. In the example shown, the smart phone ispositioned for best reception in beams 31 and 30′, and it is a simplematter from there to determine that these beams intersect in Lane 1.FIG. 3 also shows wide beam pattern 12 antennas 4 connected to WiFi 8and BLE 9 transceivers for actual data communication between theroadside equipment and the smart phone 1.

In a further aspect of the system, shown in FIG. 2, multiple BLEtransmitters, or beacons 9, can be installed across the roadway on agantry 5 and connected to high gain antennas 6. WiFi transceivers 8 mayalso be connected to the antennas 6. A high gain antenna for purposes ofthis specification is an antenna with a gain of 8 db or higher.

In an embodiment, the beacon ID and time stamp are included in thebeacon transmitted data to allow the smart phone to identify itslocation at a time stamp. The phone 1 then sends beacon ID and timestamp along with phone/vehicle identification to a remote toll server 25via the phone's common carrier cellular data connection. The BLE beacon9 transmits at a high rate, approximately once per 20 milliseconds. Thebeacon time stamp is synchronized to local system time to resolvetransactions. Specialized beacons with high gain can be used fortracking or localization.

An exemplary beacon is the iBeacon®, which uses a protocol developed byApple®. Various vendors have since made iBeacon®-compatible hardwaretransmitters that advertise their ID to nearby portable electronicdevices. The technology enables smart phones, tablets and other devicesto perform actions when in close proximity to an iBeacon®.

In an embodiment, the phone receives messages from multiple beacons andstores relevant data fields such as beacon ID, plaza and lane number,latitude/longitude, time and date, and RSSI.

As battery life on mobile devices is a key product differentiator, somedevices limit the transmit rate or the effective receive rate forwireless transceivers. For example, iPhones® apply such limits to theBLE functionality, resulting in a maximum transmission rate that is lessthan the BLE standard maximum and a diminished sample rate when thedevice is scanning for beacons; that is, the sample rate is less thanthe BLE transmission standard maximum, so samples cannot keep up withbeacons transmitting at that rate.

These restrictions are relaxed, however, when the phone is detecting aniBeacon®, so while it is in range of an iBeacon® it is able to recordBLE beacon data in background/sleep mode at nearly the same rate as thebeacon advertising rate. This requires a system architecture thatcontains iBeacons® to “awaken” iPhones® and beacons to provideadvertisements for the toll transaction. The iBeacons® must have acoverage zone that extends well upstream from the toll plaza to providesufficient time for the phones to be ready to record beacon data whentravelling through the plaza. A single antenna or multiple low gainantennas may be used to provide a wide area communications zone toaccomplish successful reception of the iBeacon message. These are usedin combination with high gain antennas used for the subsequent beaconmessages which form a more constrained communication zone. The phone maytransmit log data to a server for post processing and analysis, orpreferentially analyze it to determine lane number and transmit thatinformation to a server.

The simplest approach, when the phone is acting as a receiver and beacontransmitters are fixed across a roadway, is for the fixed equipment totransmit BLE undirected non-connectable advertisements. The format ofthe advertisement message is defined in the BLE standard, and includes31 bytes of user-defined data that can include all relevant informationfor a toll transaction. The phones operate as BLE passive scanners anddo not transmit. An individual phone would likely hear multiple beaconsas it traverses a toll plaza, and would have to process the data todetermine lane location or transfer the data to a back office forpost-processing, including lane location.

Non-connectable, undirected BLE advertisements have a minimum timeinterval between advertisements of 100 msec. This time represents 14.7feet for a vehicle traveling at 100 mph. Shorter time intervals arenecessary for accurate signal strength histories, and are also usefulfor timing coordination with existing sub-systems in a toll plaza suchas video camera systems. Connectable, directed BLE advertisements have aminimum time interval between advertisements of 20 msec, or 2.9 feet fora vehicle traveling at 100 mph. This provides much improved resolutionwhile eliciting BLE scan requests from mobiles.

Further time resolution may be achieved by including multiple BLEmodules in a beacon. For instance, two beacons can share an RFconnection to an antenna, making the effective advertisement intervalequal to 10 msec. The mobile application would have to correctlyinterpret advertisements from both beacons as coming from the same lane,a simple matter of software. Finally, a high duty cycle mode exists inBLE connectable directed advertisements, where the maximum advertisinginterval is 3.75 msec. This would provide a significant increase inresolution, perhaps more than necessary for a toll system. However, notall devices support this high duty cycle mode.

The data recorded on the phone would likely include, at a minimum, timestamp, beacon ID, and RSSI for each sample. The sample plot in FIG. 6displays BLE RSSI recorded on a phone located in a vehicle travelingthrough a lane with a Beacon overhead in the travel lane and anotherBeacon overhead in an adjacent lane. The difference in peak signalstrength between two Beacons is clear, and one Beacon is clearlystronger for the majority of the record. This concept is not restrictedto BLE, as the wireless protocol may be WiFi or any other that isavailable on a smart phone.

In an approach, multiple messages may be transmitted by a BLEtransceiver, or “beacon”, through a high gain antenna and received bythe smart phone. The high gain antenna will be generally set up on anoverhead gantry with maximum gain direction pointing towards the roadsurface or slightly up-tilted toward vehicles as they approach the tollpoint, forming a capture zone on the road where vehicles are in positionto communicate with the beacons. While the capture zones for each beaconwill overlap in a typical case of one antenna per standard-width lane,higher signal strengths tend to occur near the antenna boresight.Because the lane numbers are associated with beacons with known IDs, thelocation of the vehicle can be determined by analyzing RSSI data for thebeacons captured on the phone. The phone application 17 may evaluate thenumber of messages received and the RSSI values from each beacon todetermine the position of the phone relative to the beacons, hence thelane. The toll can then be collected from an account associated with theunique ID for the vehicle passing the toll point in that particularlane, wherein the lane/proximate antenna/beacon information is sent withthe unique ID to the toll system and or account service center. Oneapproach in this case is that the application on the phone compares thesignal strengths received from each beacon antenna to determine thestrongest one over a specified period, say 30 milliseconds. As the phonetraverses the roadway, each period has a count assigned based on thestrongest signal strength received on an antenna, the most proximateantenna or alternatively the lane of travel is determined to be theantenna or lane with the most counts in a larger second period (say 300milliseconds) or the total such counts during a the entire periodrequired to traverse the section of roadway.

Another simple algorithm to make the lane determination is to examinethe strongest N samples for all beacons and average them to create asingle number for each lane. This may be thought of as a low-orderestimate of the area under the curves, proportional to energy, andpossessing increasing accuracy as N increases. As N increases, morecalculations are required which increase the burden on the processor.Hence a proper value for N is a tradeoff between accuracy and processorburden. In practice, the number N can be arrived at through trial anderror. In the case summarized in FIG. 6, the difference in the averagesbetween the correct lane and adjacent lane is 13 dB, using N=10. Thedifference of 13 dB is also approximately equal to the peaks of thecurves. Utilizing a single peak value would provide the correct answerin many cases, but RF multipath can corrupt a single sample more easilythan several samples.

To assign the best time stamp for correlating the vehicle passage toother lane sensors, a straightforward algorithm is to use the median ofthe time stamps for the five data points with highest RSSI in theassigned lane as can be performed for example on the plot in FIG. 6.This synchronized and accurate time stamp combined with accurate laneposition allows the transaction to be accurately post-processed into thetoll system transaction.

To use the system, users download an application with the foregoingcapabilities to the smart phone. Upon download of the phone application,the user will use application-supported account management features toset up an account with the appropriate toll authority or third partyservice provider, create a link between the unique ID/addressinformation to the account, and provide a means for the settlement oftoll charges associated with the unique ID (such as a credit card).

In an aspect of the system, it is possible to determine which lane avehicle and phone are in based on messages received from multiple BLEbeacons. In an embodiment, upon receiving beacon messages and leaving aGeo-fence area or iBeacon® zone, the raw beacon log data is transferredfrom smart phone to server for transaction analysis/processing. See FIG.6 for diagram of beacons within a Geo-fence.

Alternatively, the smart phone application can simply save theBluetooth® LE beacon messages as the smart phone passes under the highgain beacons on the toll facility. The messages will contain, at aminimum, data identifying the location of the toll lane and the time thebeacon message was sent. The smart phone will normally receive multiplemessages from multiple beacons while traversing the toll plaza. A clockin the beacon establishes the time in the message and is synchronized tothe other toll equipment to a sufficient resolution (say 1-100 ms) toallow the transaction to be correlated based on the time of thetransaction with other elements of the toll system such as a vehicledetection system or a video-based license plate reading system. Thissaved data is then sent as soon as practical via any of the smartphone's data connections (Bluetooth®, WiFi, WAN data) to a server wherethe processing to determine the lane position described above isexecuted. In this case the server need not be located roadside but canbe located anywhere.

In one embodiment a Geo-fence function is used to determine when thebuffered BLE beacon messages or processed results should be sent to theserver over an available data connection. Geo-fence applications arewell known in the art and provide a function to allow a specific area tobe defined such that an alert is generated when the Geo-zone area isentered or exited. A Geo-zone can be created around the toll plaza orarea. When the area is exited an alert triggers the sending of theprocessed or unprocessed beacon data to the server for post processinginto the toll transaction. Similarly a Geo-zone can be establisheddownstream of the toll point where traffic must traverse, and entry intothis Geo-zone can also trigger the sending of buffered data to theserver for processing.

It may not be possible given the state of smart phone technology orlimitations in smart phone systems to send beacon data in real time tothe server. However, because the beacon data contains a time stampsynchronized to the toll system at the toll plaza, a toll transactioncan be generated and post-processed with other data collected from othertoll sensors proximate to the roadway to form a complete tolltransaction. For example, most toll systems include a video-basedenforcement/toll system at the toll plaza. Such systems use varioustechniques well known in the art to take a photo of the vehicle licenseplate which can later be processed and “read” automatically by acomputer. In prior art systems, the toll payment is made by an RFIDreader reading an RFID tag associated with a user account that settledto the users credit card or bank account. If this toll payment is made,the photo taken of the license plate is associated with the vehicle neednot be processed and can be discarded or stored according to policy. Ifa payment is not made, either a violation against the vehicle owner ofrecord or a video-based toll against an account or the vehicle owner ofrecord is processed.

One advantage of post processing the transaction data is thatsubstantially all of the data points collected on the transactionbetween the beacon and the smart phone can be collected and used todetermine the lane position and to determine a time stamp for thetransaction that best represents when the vehicle passed under theantenna. More data typically means better quality output result foralmost any reasonable algorithm used to determine vehicle positionrelative to the beacon antennas.

Typically a trigger system is used, employing one of many vehicledetection technologies known in the art, to determine the vehicle'slocation on the roadway to take the photo of the license plate. In orderto allow toll payment by smart phone rather than RFID tag, the phoneapplication requires the user to establish an account with the tollauthority, or through a private third party account consolidator whosets up a consolidated account for the user with multiple toll agencies.At that time an account identifier is established by the application orby an account server in communication with the application over aninternet connection supported by the smart phone. That accountidentifier is sent by the smart phone when the processed or unprocessedbeacon data is sent to the server, typically after a Geo-fence oriBeacon zone exit event occurs to trigger the sending of this data. Thetrigger point for the license plate photograph is aligned to thedirection of maximum gain of the antenna, allowing the determined travellane to be associated with an accurate time stamp. As this time stamp isalso synchronized with the video system, the beacon transaction can becompared to the video transaction to ensure they are from the samevehicle, eliminating the need for the license plate photo to beprocessed.

Typically, this transaction from the smart phone will not occur in realtime. This is because the sending of the data will be triggered by anevent such as a GeoZone exit (or entry) event, iBeacon read zone exit,or RSSI residing below a threshold for an elapsed time, all of whichoccur after the vehicle has passed through the toll plaza. Additionalsources of latency in the communications network will add to this. Allof the data collected as the vehicle traverses the plaza is availablefor the algorithm that determines lane and time of passage. It alsoimplies that the photo data and any other associated sensor datapertaining to the toll transaction must be stored for some period oftime to allow receipt and processing of the data from the smart phone tocreate the toll transaction, so that it may be post processed againstthis stored data as described above. The minimum period of storage, andthe resulting storage capacity are determined based on the maximumexpected delay in sending and processing the smart phone data so that itmay be post processed. Alternatively, all such data may be permanentlystored according to policy.

In Apple's® iOS® operating system, applications that are not activelybeing used by the user operate in the background. Usually theseapplications cannot process data or access resources to preserve batterylife. In the contemplated system it is highly advantageous to avoid theneed for user action, as a matter of customer convenience and drivingsafety. There are some exceptions in iOS that will allow some processingtime to be allocated to an application running in the background. Oneexception involves the use of geographical areas. Upon entering ageographical area, the phone application can be automatically launchedor elevated in priority by the operating system. Upon receipt of BLEdata expected by or intended for the phone application, iOS will providea specific allotment of time for the application to process the BLEdata. In one embodiment all of the stored BLE messages received areuploaded to the server over the WAN data link using a web services call.

Another approach to resource conservation, while the toll applicationsits in the background, is to create iBeacon® zones in the roadways thathave beacon zones within them. An iPhone® will not log iBeacon®advertisements at a rate faster than one per second, regardless of theiBeacon® advertisement rate. It will record beacon advertisements muchfaster in general, and approximately at the same rate as theadvertisement itself, if the iPhone® is in range of an iBeacon®.

In a further embodiment, transaction data is stored in a file on thephone. Data can be received and logged even with the phone in sleepmode. Data is downloaded to a server with no user intervention,triggered by an event such as a Geo-fence trigger described above.Because data will not be downloaded in real time, transactions must bepost-processed into the toll transaction to be correlated with datataken at the toll area, such as video or camera recording of licenseplate, and vehicle detection.

In one alternative, a transponder device is installed in theconventional electronic toll lane in a similar fashion to how testtransponders are used today. The transponder acts as a repeater of theinformation transmitted by the smart phone. The transponder contains aBLE or WiFi transceiver which receives transaction information from thephone to include the phone unique ID. When interrogated by a reader, thetransponder will mimic the type of message sent in conventionalelectronic toll messages with an account ID associated with the phoneunique ID. In this way the system described above can be implementedwith minimal or no changes in the software and integration of the tollsystem or conventional back office/service center.

In another embodiment, BLE beacons broadcast advertisements via antennas6 that are typically dispersed one per lane, although two per lane maybe used, or fewer than one per lane may be used. When received in anapplication resident on the smart phone 17 these advertisements triggerresponse messages sent by either the BLE radio 9 or WiFi 8 radio in thesmart phone with a data response similar to how prior art active RFIDtransponders behave today. Simultaneously, these BLE Beacon messagescould trigger return messages to the toll system over any combination ofWiFi, BLE or common carrier WAN data connection present on almost allsmart phones. These responses contain information that is sent to aservice center for the settling of toll collection related to thevehicles' use of the roadway. This information is transmitted to theservice center either by a toll system network of the type commonly usedtoday (in the case of WiFi or BLE return message) or via the WANconnection 10 directly from the smart phone to the service center, orany combination thereof which provides for redundancy of messaging andtherefore enhanced reliability. In all cases the return message withunique identifier is received at the service center where accountsettlement is performed, and the toll is settled to the accountassociated with it. In a further embodiment, a smart phone is a receiverinitially scanning passively for BLE advertisements from the beacons asit enters a capture zone. Upon decoding an advertisement, the phoneoptionally sends a BLE Scan Request to the beacon. The request payloadconsists of the beacon address and the phone MAC address. The beaconissues a BLE Scan Response in response to each received Scan Request.The total number of scan responses represents the number of transactionswith a phone.

The timestamp for the transaction resides in the scan request payloadand must match the timestamp for other toll systems (i.e. videocameras), within an allowable tolerance.

At the completion of the transaction, the system composes an encrypteddata packet containing the phone MAC address, time and date, plaza andlane ID. This is sent to a back office via typical means, for exampleeither over land line communications such as an internet connection orwirelessly such as by a cellular data connection, and checked againstvideo data for violations.

In an implementation utilizing single-beam antennas, each lane willtypically contain an overhead antenna 6 with high gain, circularpolarization, and sufficient bandwidth to cover the entire ISM bandaround 2.45 GHz. The antenna points approximately downward, reducingpotential for cross lane communication. By contrast, antenna pointingangles near horizontal can allow large vehicles to block the direct RFpath of smaller vehicles in the same lane, and multiple phones indifferent lanes to be transacted with at relatively longer distanceswhere the beams have spread significantly. Pointing downward, therefore,allows easier control of the capture zone.

A high gain antenna with low side lobes and a sharp beam roll off willminimize RF leakage into the adjacent lanes. This pattern must beconsistent across the entire ISM band because BLE uses RF frequenciesspanning the band.

Circular polarization is preferred in the beacon antenna because of thevariable antenna pattern in the phone. Linear vertical or horizontalpolarization could be used, but circular polarization is preferred so asto make the communication link to the phone less sensitive to theorientation of the phone in the vehicle. This allows the user moreflexibility for the phone's location inside the vehicle, including theseat, in pocket, on the vehicle's dash board, or in its center console,creating good RF link performance unaffected by orientation of thephone. Most antennas targeting 2.45 GHz devices in mobile phones havenulls in each plane. The location and depth of the nulls is dependent onfrequency and polarization, and a circularly polarized Beacon antennawill provide polarization diversity.

Frequency diversity is a de-facto feature of the system when usingwireless protocols that utilize a sufficiently large RF frequency band.A large operating frequency band causes phone antenna nulls and RF fadesto move as frequency changes. In a BLE system, for example, advertisingchannels hop between 2402, 2426, and 2480 MHz. The antenna operatingband must be at least this large to take advantage of this.

The required antenna features of the system described above enhancechances of the in-lane beacon transacting with the phone, as opposed tothe adjacent-lane beacon. It does not entirely rule out cross lanetransactions, so an appropriate system will monitor the number oftransactions on all beacons for a specific phone and choose the travellane appropriately.

With smart phones acting as transmitters, the receiving antennas locatedin the toll plaza may take multiple forms. One embodiment is a pair ofmulti-beam antennas straddling the roadside to enableangle-of-arrival-based lane determination. A common form for themulti-beam antennas are planar arrays with Butler matrix feed systems.Butler matrix antenna configurations are known in the art but can beuniquely applied in this case with either the WiFi or the Bluetooth® LEradio signals to track vehicles in which the phones are present andassociated. The multi-beam antennas can be used on their own for bothcommunications and tracking, but may also be used with a set of low gainantennas where the low gain antennas cover the entire area of interestto allow more time for reliable communications and the multi-beamantennas are used for tracking only or primarily for tracking. TheButler matrix is a well-known beam-former, producing N beams from Ngroups of radiators.

FIG. 5 shows the results of experimental evaluation conducted with twomulti-beam antennas installed roadside. The test results showedsignificant ability to locate the vehicle position across six availablelanes of travel. The graph shows post-processed data: the computed lanenumber as a function of time, and the total number of hits for eachlane. Multipath is evident in hits for lanes beside lane 3 (the actualtravel lane). One car at a time was tested.

These experiments were conducted with a 2.45 GHz radio in the vehicleunder the dash on the left side of the vehicle, which is a non-idealposition for the transmitter in the vehicle because the signal mustreach the receiver via multi-path. Similar, but less severe multi-pathcan be expected based on the typical locations users will have theirphone in the vehicle, be it in the user's pocket, belt, purse, cupholder or passenger seat. All of these locations will potentially seemulti-path between the smart phone and exterior antennas, but probablyless severe than the conditions of the experiment. Notwithstanding themore severe multi path conditions for the experiment, reasonably goodposition results were obtained in determining the lane of travel byassigning the transmitter to a lane position by summing the number ofpoints where the peak beam signal strength of the Butler matrix antennasindicated an intersection point in a particular lane and assigning thelane position to the lane with the greatest number of such points as thevehicle traverses a section of roadway.

To use the system, users download an application to the smart phone.Upon download of the phone application, the user will use applicationsupported account management features to set up an account with theappropriate toll authority or third party service provider, create alink between the unique ID/address information to the account, provide ameans for the settlement of toll charges associated with the unique ID(such as a credit card).

The test results FIG. 5 show significant ability to locate the vehicleposition across six lanes. The graph shows post-processed data: thecomputed lane number as a function of time, and the total number of hitsfor each lane. Multipath is evident in hits for lanes beside lane 3 (theactual travel lane). One car at a time was tested.

In another embodiment, the smart phone application is configured tosupport the accurate and secure self-reporting of miles driven bytaxpayers in jurisdictions where taxes are collected based on the numberof miles driven in the jurisdiction. As a possible way to meet policyobjectives, California and Oregon have pilot projects and considerationis being given to similar taxation system by the U.S. FederalGovernment. However a practical, private, easy, accurate and secure wayfor user to report the mileage and corresponding tax has been lacking.

The basic reporting approach involves installing BLE beacons atlocations convenient to the motorist such as gas stations, oil changefacilities, smog check stations and car washes, called reportingfacilities. In the preferred embodiment drivers self-report the mileageand pay the tax periodically, perhaps once per quarter or per year. Thephone application of the invention makes it easy and secure to reportmileage.

The design of the phone application is such that the user enters areporting facility and parks in a designated location designed to becovered by the BLE beacon. The beacon data includes location data and asecure identifier. In one embodiment the secure identifier is anencrypted combination of the time and location information. Thelocations are selected and high gain antennas placed such that no morethan one vehicle can be parked in a designated location simultaneously.

The phone application recognizes the beacon, processes the data, andstarts the procedure. The user is prompted to take a photo of thevehicle odometer reading, and the application records the fact that thephoto was taken proximate to the secure beacon and a specific date andtime. Next the user is prompted to take a picture of the VIN or licenseplate number, and the application records that the VIN is also proximateto the same secure beacon at the same date/time (within a tolerance).This ensures that in fact the odometer photo and the VIN or licenseplate number photo are from the same vehicle.

The phone application applies OCR techniques to the odometer reading tocreate a data element and compares this reading to the previous reading.The application calculates the tax based on the difference in mileagefrom the previous reading.

Once the tax owed is calculated the phone application then prompts theuser to make payment by electronic check, ACH, or credit card, Pay Pal®or other known payment systems. These payment methods can be newlyestablished at the time of payment or stored at the user's preference.The user makes payment and an official receipt is sent to the usersstored e-mail address.

If a user wishes to account for miles driven on non-taxable roads thatmight be exempt from the tax, such as out of state or private roads, aBLE beacon can similarly be placed at the access point to thosefacilities. For example, BLE beacons can be installed at the stateborders to account for out of state miles. The phone application detectsthese border beacons to validate that the vehicle has indeed crossed thestate line. Alternatively two beacons in sequence could be used tovalidate the direction of travel at the state line. The secure borderbeacon location data is stored in the application. The phone applicationthen sets up a large position change feature on the phone, so that thephone application is activated by the phone upon a significant change inposition, or after a certain period of time has elapsed. Uponactivation, the application evaluates the data from at least one GPS fixto determine the estimated miles driven from the border beacon location.Upon each subsequent activation of the application on the phone a newGPS fix is taken and an incremental number of miles driven out of state.This process continues until the phone crosses another border beaconsystem indicating re-entry into the state (or alternatively, a GPSposition fix within the state). The total accumulated miles out ofdriven out of state can be determined.

In addition, if policy dictates the need to collect mileage based tax orfee at different rates on different types of roadways this can beaccommodated by the system design. For example, if a different rate isto be charged for controlled access highways than arterials, beacons canbe placed on the controlled access points to identify entry and exitpoints which allow the determination of total miles driven on controlledaccess highways. Those miles can be accumulated in a separate buffersuch that at the time of tax payment calculation the tax due can bedetermined based upon the differentiated miles driven. Similarly, whenmiles are driven on a toll facility which might typically be exempt froma mileage charge, BLE beacons on the toll facility can be segregated tocalculate the correct adjustment to the tax owed at time of payment. Ofcourse as described in this disclosure the BLE beacons can work with thephone application to be the primary method of toll collection, providinga seamless approach for the user to pay for services rendered.

Consistent with embodiments described herein, the following describes amethod to securely and conveniently enroll user smart phones or similardevices that may be used in systems as described herein in an accesscontrol system to provide access to a limited-access facility via asmart phone running a dedicated access application. Manually entering along alpha numeric identification key into an access control system foruse with a smart phone or other wireless-enabled personal device,including smart watches and tablet computers as an access transponder isboth tedious and can be prone to operator error and fraud. Also, amechanism is needed that can allow access by the user's personal deviceto be easily revoked by the gate's manager and by users who lose orreplace devices. As described herein, utilizing access cards havingunique user identification and serial numbers that may be scanned into asmart phone, allows easy enrollment/disenrollment and authorized usermanagement of smartphones used as keys in an electronic gated entry oraccess control system.

FIG. 7 is a block diagram of an exemplary access control subscriptionsystem 200 consistent with embodiments described herein. System 200 maybe used in conjunction with automatic gate opener systems equipped withBLE or WiFi transceivers to allow authentication with use of a smartcellular phone. System 200, as shown in FIG. 7, consists of anelectronic gate controller system 202 having a BLE transceiver 204, auser smart phone 206 having smartphone-based facility access applicationsoftware 208, a smart phone readable identification/authorization card210 with identification card data, and a server 212 associated with asystem operator and configured to authenticate the authorization carddata, as described below.

An exemplary use of this system is with an electronically controlledgate system installed at facilities such as a gated community orcorporate parking garage. The term gate includes any vehicle accessbarrier such as, but not limited to, retractable treadles, a pivotingbar, a bar having a first portion that pivots and a second portion thatremains substantially parallel with the roadway surface; retractablebollards, a retractable door, a hinged or linearly retractable fencegate and the like. Users who wish to use their smart phone or similardevice such as a smart watch to activate the gate opener would firstinstall the software application 208 on their compatible smart phone.The operator of the gated facility provides a new user an accessauthorization card 210 one example of which is shown in FIG. 8. The newuser scans the access authorization card with the mobile application 208installed on their smartphone 206 to retrieve or otherwise obtain theauthorization card data embedded therein. In response, smart phone 206communicates the authorization card data to server 212. If server 212determines that the access authorization card is valid, access to thegate will be granted each time the phone is presented at the gate. Theuser will be able to access the gate until the authorization expires, orthey are blacklisted by the gate administrator.

The access authorization cards (example shown in FIG. 8) may contain aQR code or similar graphic data representation to automate the processof entering the card's data into a phone. The access authorization card900 may include a card serial number 902, transponder ID number,expiration date 906 and other information such as instructions and a URLto the service provider's webpage. A transponder ID number may beencoded within a QR code 904 on the access authorization card and not beprinted in a human readable format on the access authorization card 900.These ID numbers may be issued and printed on cards (in graphic formsuch as QR codes) in a randomized, non-sequential order to preventmalicious users from predicting other ID numbers for unauthorizedaccess. The serial number 902 may be written in plain text (humanreadable). The transponder ID number will be a large number (e.g. 16digits) and non-sequential to prevent unauthorized cards from beingproduced. A malicious user could not simply guess the next authorizationcard available. In an aspect of the system, during manufacture, aremoveable (e.g., perforated) stub may be initially attached to theaccess authorization cards that contains identical information. When theauthorization card is assigned to a user, the stub may be removed andretained by the facility manager to keep a record of which card wasgiven to which user. As an additional security feature, the transponderID's may be encrypted on the access cards.

Serial numbers 902 can be sequential and used to track production andsales of access cards, as well as used to link cards (e.g., in sever212) to specific electronically-controlled access gates. When an orderis placed for access authorization cards by a facility, the purchaserwill also indicate the gate ID number associated with their gatehardware. Before sending a shipment of new cards, the service providerwill first link those new cards, by serial number, to that gate ID, sothat the operator will only allow those cards to open that specificgate.

Server 212 may be used as an authentication server for the accessauthorization card 210. FIG. 9 is a flow diagram illustrating anexemplary process 300 for activating a user authorization card 210. Asshown in FIG. 11, process 300 beings when an authorization card 210 isinitially scanned with end user's smart phone 206 (block 302). Forexample, a user may activate smart phone application 208 and capture theQR code 904 provided on card 210. Data from the card QR code 904 is sentto server 212 by smart phone 206 (block 304). This transmission may beover a cellular data network or an internet connection. Upon receipt ofthe QR code data, server 212 identifies the card's serial number and IDnumber in a database to see if these numbers have previously been used(block 306). At block 308, server 212 determines, whether card 210 hasbeen previously unregistered (i.e., unused). If it is determined thatthe card 210 has been previously registered (block 308—no), server 212will reject card 210 (block 310) and deny access to the gate.

However, if it is determined that card 210 has not been previouslyregistered (block 308—yes), and is not past its expiration date (notshown), server 212 may determine the gate ID (or ID's of multiple gates,if applicable) associated with card 210 (block 312), and return thatinformation to the user's smart phone (block 314) as well as enable thatsmart phone to operate the gate that was linked to the card scanned(block 316). The final piece of information that the server may send tothe user phone is when the access to that facility will timeout (block318). As an example, access may timeout one year after the validation ofthe card or on a fixed date, such as the end of a calendar year orschool term year.

Access authorization cards 210 may be distributed by the gate's operatorto all drivers who are allowed access to the gate, using their smartphone. When a gate administrator receives a batch of cards, they willreceive a list of the transponder ID numbers associated with each serialnumber of the cards in the batch. These transponder ID numbers are usedas the ID numbers programmed into the gate hardware white-list by thegate's administrator.

Once a phone is activated with a valid access authorization card asdescribed above and in FIG. 9, the end user keeps the gate accessapplication running in the background of their phone or similar device.When they approach the gate, the gate reader hardware 204 and the phone206 will communicate via BLE or WiFi, as applicable, and the gatecontroller system 202 will receive from the transponder ID number fromphone 206. Since gate controllers 202 may be using any number ofpreexisting legacy tag protocols to process dedicated legacytransponders (Wiegand, eGo®, etc.), reader hardware 204 installed at thegate may translate the user's transponder ID into a format readable bygate controller 202 used at that specific facility. The translatedtransponder ID number may be read by gate controller 202 as it wouldread a legacy tag, and if the transponder ID number is white-listed, thegate will open for the user. See the above description for a furtherembodiment of converting a smart phone transmitted ID to a legacytransponder signal.

The cards provide for ease of enrollment for new users. With thissystem, the gate administrator only needs to issue an accessauthorization card to a new user. Upon receipt of a batch of accessauthorization cards, the gate administrator could whitelist all accesscards immediately, thus removing the step for an administrator to enterin new users to the system each time a card is given out. The only timethe gate administrator needs to intervene after that is to revoke accessfor a user, or allow that card to expire without renewing the ID orissuing a new card. If a gate administrator wants to remove a person'saccess, they will simply remove their transponder ID from the gatecontroller's whitelist as done with the other forms of access availableat that gate.

Another aspect of the card embodiment of the smart phone as transpondersystem is that it turns the concept of permission-to-enter into aphysical, tangible item that can be physically transferred to someone.For example, in an apartment complex with a gated parking lot, anauthorization access card can be issued to a new tenant along with thekeys as part of the lease signing. For the new tenant, the card is aphysical item showing they have been given access to the facility, whilefor the apartment complex, the batch of undistributed cards are part oftheir inventory that can be easily managed, tracked and safeguarded justas organization manages their inventories of remote controls, parkingpermit stickers and hangtags.

Another aspect of the access authorization card embodiment of the smartphone as transponder system is that the cards can move the up-frontcosts associated with the system from end user to facility manager. Endusers might be unwilling to purchase a paid phone application or submittheir credit card information to download a paid phone application, thusthe phone application would be distributed free of charge to end users,while the access authorization cards would be sold to facility managers.At that point it would be up to the facility managers to distribute thecards as they wish, either for free, or for a fee (with or withoutmarkup), just as is done with remote controls, RFID tags, parking permitstickers and hangtags.

Another aspect of the access authorization cards is that they arenon-transferrable. In some communities, a pin number is assigned to beentered into a keypad for access. These PIN numbers are easilyforgotten, or leaked to unauthorized persons. The phone as transpondersystem with a unique ID card provides the same security gained by remotecontrols or RFID tags, however, there is no physical item that needs tobe returned to a facility manager if the user is moving or no longerneeds access. Nor is there an additional piece of hardware for the enduser to lose. The access authorization cards are one time use only, andcan be discarded after they are scanned by a phone. Remote controls havebatteries that need replacement, and the units themselves can wear outand break. Traditional keys can break, be lost or stolen andunauthorized copies can be made. Many facilities that give out accessdevices (e.g. keys, RFID key fobs, proximity cards, remote controls)require the user to put down a cash deposit, or be financiallyresponsible for the items in case of damage or loss. This systemeliminates the need for a deposit, or anything to be returned, yetprovides the same level of security.

Although the invention has been described in detail above, it isexpressly understood that it will be apparent to persons skilled in therelevant art that the invention may be modified without departing fromthe spirit of the invention. Various changes of form, design, orarrangement may be made to the invention without departing from thespirit and scope of the invention. Therefore, the above-mentioneddescription is to be considered exemplary, rather than limiting, and thetrue scope of the invention is that defined in the following claims.

No element, act, or instruction used in the description of the presentapplication should be construed as critical or essential to theinvention unless explicitly described as such. Also, as used herein, thearticle “a” is intended to include one or more items. Further, thephrase “based on” is intended to mean “based, at least in part, on”unless explicitly stated otherwise.

The invention claimed is:
 1. A system for locating a user devicecomprising: a server; an application configured to execute on a userdevice and a first signal receiver, wherein the application comprisesidentification data associated with an account related to a tollpayment, and wherein said application is configured to cause said userdevice to periodically transmit first messages comprising saididentification data via Bluetooth Low Energy (BLE) or other ultra highfrequency (UHF) signals, wherein said first signal receiver isconfigured to: receive said first messages from the user device,determine, for each of the first messages, a received signal strengthindicator (RSSI), and communicate said identification data and the RSSIfor each of the first messages to said server, and wherein said serveris configured to: receive second messages from a plurality of signalreceivers including the first signal receiver, wherein each of thesecond messages comprises an RSSI, and determine a location of said userdevice relative to a lane of travel based on the RSSIs included in eachof the second messages.
 2. The system of claim 1, wherein whendetermining the location, the server is configured to: identify ones ofthe second messages associated with each of the plurality of signalreceivers with RSSIs that exceed a predetermined RSSI threshold, anddetermine the location of the user device based on which of theplurality of signal receivers is associated with a greatest number ofsecond messages having RSSIs exceeding the predetermined threshold overat least one period of time.
 3. The system of claim 2, wherein saidplurality of signal receivers comprise: the first signal receivercomprising a first antenna having a first receiver antenna beam pattern,and a second signal receiver comprising a second antenna having a secondreceiver antenna beam pattern.
 4. The system of claim 3, wherein saidfirst receiver antenna beam pattern and said second receiver antennabeam pattern are configured to allow determination of the location ofsaid user device across a roadway.
 5. The system of claim 4, whereinwhen determining the location, the server is configured to: comparefirst RSSI data points exceeding said RSSI threshold and second RSSIdata points exceeding said RSSI threshold.
 6. The system of claim 5,wherein said first receiver antenna beam pattern and said secondreceiver antenna beam pattern partially overlap.
 7. A system forlocating a user device comprising: an application configured to executeon a user device, wherein the application is configured to receivecommunications from a plurality of transceivers associated with a tollpayment system, wherein said application is configured withidentification data associated with an account related to toll paymentto the toll payment system, and wherein said application is configuredto: receive messages from the plurality of transceivers, wherein each ofthe messages includes an identifier associated with one of the pluralityof transceivers, determine a received signal strength indicator (RSSI)associated with each of the received messages, and determine a locationof the user device relative to a lane of travel associated with the tollpayment system based on which of the plurality of signal transceivers isassociated with a greatest number of messages having a highest RSSI overat least one period of time.
 8. The system of claim 7, wherein said userdevice communicates the location to a server associated with the tollpayment system.
 9. The system of claim 7, wherein said user devicecommunicates the location to a signal receiver associated with the tollpayment system.
 10. The system of claim 7, wherein when determining thelocation, the application is configured to identify messages that exceeda predetermined RSSI threshold.
 11. The system of claim 7, wherein saidapplication is further configured to determine RSSI data pointsassociated with a plurality of antenna beam patterns.
 12. The system ofclaim 11, wherein the plurality of antenna beam patterns are configuredto allow the application to determine the location of said user deviceacross a roadway.
 13. The system of claim 12, wherein when determiningthe location, the application is configured to: compare first RSSI datapoints exceeding an RSSI threshold and second RSSI data points exceedingsaid RSSI threshold.
 14. The system of claim 13, wherein said at leastsome of the plurality of antenna beam patterns overlap partially.